Speed of Spiderman - Introductory Physics - Solved Paper, Exams of Physics

Download Speed of Spiderman - Introductory Physics - Solved Paper and more Exams Physics in PDF only on Docsity! PHYSICS 8A - Buehler Summer 2006 Midterm 2 Thur., Aug 3, 2006, 6:10-7:30 PM ; al NAME : Ze 1+; ‘ Quek thlossy Sof “3 (Pe poll clock dhen \ SID #: ibe st aN pork ay yes! ERMAN S Disc #: Dise Day & Time: - A formula sheet is provided as the last pages of the exam. - Read through the exam first, and do the problems you are comfortable with first. Don’t spend all your time on one problem at the expense of not trying the others. - Calculate all numerical answers to 3 significant figures, provide units for all numerical answers. - As always, you must show your work and/or explain your reasoning. CORRECT ANSWERS WITH NO SUPPORTING WORK OR EXPLANATION RECEIVE NO CREDIT! [20 /20 220 [20 [20 100 Gy) By Ge} bo} 1. (20 pts) Unlike the current movies, in the original Spiderman comic book, Spidey couldn't shoot webs out of his body. Instead he had a wrist device that shot out a man- made “web” which was basically a high strength string. Assume this string can support three times Spiderman’s weight without breaking. To save Lois Lane, Spiderman, of mass m, must swing down from the top of the building on his “web”, of length |, from an initial angle of 60° and grab Lois, also of mass m, and swing away. a) What is the speed of Spiderman at the bottom of the swing, just before grabbing Lois? b) Can Spiderman rescue Lois Lane without his “web” breaking after he grabs her? [a= 8 pls, b= 12 pts] : ay cde (FY 2) Norms Se 5 Peon Cay “ KO 4 ? E . : Ke, af E, KE, ° a Jens, a ow “Tos DLS me edule nr <P ms 3. (20 pts) To test a syringe, the doctor holds the syringe vertically and pushes on the plunger. You (the patient) notice that the medicine shoots 70 cm above the tip of the needle. The syringe is 15 cm long, from plunger to tip of needle. Assume the medicine essentially has the density of water (1000 kg/m’). 15cm push a) What is the pressure just above the plunger as the doctor pushes on it? b) if in testing, the doctor pushes out 0.2 m] = 0.2 cm’ of medicine in | sec. What is the diameter of the hole in the needle? [a = 8 pts, b = 12 pts] Deen A >> ter So vy SO Benth A te a) Ayply Benet C © Lye yaykd = dpe sgh 0, - P, BE «yaks + Gooo (4 YC ss | ~ 1 ofxi* | 2 net wt Se i! —_ om b> Agply owl Bec rises ‘she > KL + et ry he 4, (20 pts) [ Parts a) and b) are INDEPENDENT ] a) A small wooden cube of mass, m, and side, a, is released from rest and floats upward from the bottom of a swimming pool filled with water, p,, of depth, H. You may assume a << H and that the drag force is constant. The cube reaches the surface with velocity, v. What is the average drag force on the cube? . [a = LO pts] . : Ke H me Foy > ) ode Ot Ot fey Hoo Mey H v Foy Hom os H- dmv = Fag HL 3 é “ 2 io - ay? = Qh _ ke a b) You push a solid disk shaped merry-go-round of mass M and radius R with a tangential force F. You run along the outside of the merry-go-round so thal you always are pushing tangentially. Your maximum running speed is v,,,,-. For how long can you push the merry-go-round? [b = 10 pts] 5. (4 pts each) Write letter of correct answer in box. EMPTY BOX GETS ZERO POD I You (Mass = M) are standing on a frictionless surface. You are L meters away from a block (Mass = m) at rest on the same surface. You begin pulling horizontally on the block with a massless rope. After t seconds, the block has moved a distance x,. For the system of you and the block, which is true? e 1S Cons. 27 Slomentum is not conserved because objects go from at rest to some speed. b) Kinetic Energy is not conserved because objects go from at rest to some speed. Carte ef mas Dt ~eyCenter of mass moves left as block gets closer to you. meas om FP _@yThe momentum in the y-direction changes because of the impulse of the glace S tension force. 7 ¢) More than one answer is true. IL. You have to get a solid ball of mass M and radius R that is resting on the Ba ground to your friend who is leaning out a second floor window at height H. Consider the two scenarios Eo 2 Gh 7 NFO vl © 5 oly ey Roll ball without slipping so it goes up and off the ramp to the ; fl S f c window. x he, [l Throw ball straight up lo window. Which takes less cnergy on your part? fe a) Throwing e™ b) Rolling ¢) They require the same enorgy since the final height is the same. d) Not enough information is provided Ewin G& C4 w= molt Eta OS OF Gan z ws u Kea te